Subjective: The following part of this article is based upon the editor's personal experiences and opinions, and therefore may not be applicable for all readers.
Tatiana's Fortify will be very helpful to this level as it allows you to restore most of your units to full health which will be necessary after Duma's Upheaval that damages your entire team. Silque's Illusionary Dread Fighters will also be useful in keeping off all of Jedah's Mogalls. Jedah will be just as hard to beat so you should take out Marla and Hestia before fighting Jedah. Jedah however will not directly attack you so he is not necessary to fight before Duma. Alm must use the Falchion to defeat Duma once Duma has dropped below 52 hp.